My DD was 2 years 3 months when we put her in her big bed. We tried the rapid return, and after 2 hours for a few nights in a row of putting her back in bed (finding her pretending to be a puppy on the floor of her room), we gave up and lay with her or say next to her. Now, 6 months later, she puts herself to sleep again like she used to in the cot. I know it's not ideal, but laying or sitting with her was much easier for us. There were definitely nights where she would go to bed later because I was getting DD2 to bed and DH was away/working late.